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Title: Regulation of ATP-sensitive K sup + channels in insulinoma cells: Activation by somatostatin and protein kinase C and the role of cAMP

The actions of somatostatin and of the phorbol ester 4{beta}-phorbol 12-myristate 13-acetate (PMA) were studied in rat insulinoma (RINm5F) cells by electrophysiological and {sup 86}Rb{sup +} flux techniques. Both PMA and somatostatin hyperpolarize insulinoma cells by activating ATP-sensitive K{sup +} channels. The presence of intracellular GTP is required for the somatostatin effects. PMA- and somatostatin-induced hyperpolarization and channel activity are inhibited by the sulfonylurea glibenclamide. Glibenclamide-sensitive {sup 86}Rb{sup +} efflux from insulinoma cells is stimulated by somatostatin in a dose-dependent manner (half maximal effect at 0.7 nM) and abolished by pertussis toxin pretreatment. Mutual roles of a GTP-binding protein, of protein kinase C, and of cAMP in the regulation of ATP-sensitive K{sup +} channels are discussed.
Authors:
; ; ;  [1]
  1. (Centre de Biochimie du Centre National de la Recherche Scientifique, Nice (France))
Publication Date:
OSTI Identifier:
5300376
Resource Type:
Journal Article
Resource Relation:
Journal Name: Proceedings of the National Academy of Sciences of the United States of America; (USA); Journal Volume: 86:8
Country of Publication:
United States
Language:
English
Subject:
59 BASIC BIOLOGICAL SCIENCES; MEMBRANE TRANSPORT; PHYSIOLOGY; PHORBOL ESTERS; BIOLOGICAL EFFECTS; RUBIDIUM 86; UPTAKE; SOMATOSTATIN; AMP; ATP; PHOSPHOTRANSFERASES; POTASSIUM COMPOUNDS; RATS; TUMOR CELLS; ALKALI METAL COMPOUNDS; ALKALI METAL ISOTOPES; ANIMAL CELLS; ANIMALS; BETA DECAY RADIOISOTOPES; BETA-MINUS DECAY RADIOISOTOPES; CARCINOGENS; DAYS LIVING RADIOISOTOPES; ENZYMES; ESTERS; INTERMEDIATE MASS NUCLEI; ISOMERIC TRANSITION ISOTOPES; ISOTOPES; MAMMALS; MINUTES LIVING RADIOISOTOPES; NUCLEI; NUCLEOTIDES; ODD-ODD NUCLEI; ORGANIC COMPOUNDS; PHOSPHORUS-GROUP TRANSFERASES; RADIOISOTOPES; RODENTS; RUBIDIUM ISOTOPES; TRANSFERASES; VERTEBRATES 550201* -- Biochemistry-- Tracer Techniques